1. Field of Invention
This invention relates to mobile lighting units, more particularly to high-wattage, high-intensity mobile and adjustable lighting units.
2. Description of Problems in the Field
The uses and applications of high-intensity mobile lighting units are numerous and diverse. Mobile lighting systems have become increasingly important in light of the development of color television, which requires large amounts of bright light to reproduce accurate colors. Other examples include nightime lighting of athletic fields, primary and background lighting for motion pictures, lighting for shows and concerts, and lighting in times of emergencies.
A good and functionally useful mobile lighting system must be designed to be strong in the following areas: compactness; efficacy (maximum usable light per watt of power consumed); daylight quality; photometric versatility: high efficiency; lightweight; ruggedness; ease of operation; compatability (no noise or static or too much heat on the subject or equipment); and economical cost of operation and maintenance balanced against other systems.
The starting point for the design of a lighting system is deciding what type or types of lamps are to be used to attain the desired light intensity. Prior portable, mobile lighting systems have utilized traditional lamps, such as incandescent, mercury vapor and any number of gas-arcing lamps, to achieve this purpose. Problems with traditional lamps is that their low intensity level requires a large number of lamps be used, their efficacy and efficiency is not optimal, and problems exist in maintaining daylight-type illuminiation, as well as dark, uneven spots on the playing field.
Recently, high-wattage metal halide lamps have been developed which significantly improve upon some of the deficiencies of standard lamps. However, these metal halide lamps, referred to as HMI lamps (which stands for hydrargyrum (mercury), medium, and iodides) have problems which have prevented their prior use in mobile lighting systems.
A primary problem with the use of HMI lamps, in any system, whether stationary or mobile, is that when used with reflectors, such an intense heat is geneated by the focused light that it may cause the lamp itself to brake from heat fatigue. This is especially true when the lamps are mounted in alignment with respect to the axis of the reflector so that an optimal amount of reflective focusing can take place. As a result, as generally used now, the high wattage HMI lamps cannot be mounted in reflectors in such a way to produce the best and most efficient focused light. In particular, HMI lamps have not been mounted along the center axis of hemispherical disc reflectors at their most efficient position because of the above mentioned problems.
Additionally, problems may be encountered with the mounting of the HMI bulbs. They are comparatively fragile. This problem is amplified considerably when using HMI lamps in portable mobile units where they are subjected to much more jostling and shock. A proper shock-dampening mounting system must maintain the exact positioning of the bulb which should not be compromised by the dampeners. To obtain maximum efficiency, particularly for mobile units, exact placement must be maintained; a misalignment of as little as a 16th of an inch may severely reduce light efficiency.
Mechanically cooling susceptible areas of the lamp to prevent breakage, presents certain inherent difficulties. The problem to be overcome is that the seals of the HMI lamps must be maintained so that they are neither too hot nor too cool. Any substantial variation on either side, must not only cool the lamps to prevent lamp breakage, but must not be so great to produce a change in the color and intensity of the light. The temperature of the seals must not exceed 280.degree. C. to prevent failures by oxidation. The use of fans to cool the seals may result in over-cooling which would increase the color temperature of the lamp, resulting in reduction in color quality. Also, one must not use complex hardware for mobile structure which unfavorably increases the weight of the total light structure.
Finally, the factors of compactness, lightweight, ruggedness, and economy dictate that a mobile light unit should have as few light-reflector assemblies as possible, while simultaneously producing a maximum output of light.
Heretofore, the limitations of conventional lamps have prevented any significant improvement in reducing the number of lights that need to be used for the varying illumination purposes desired of a mobile lighting unit. The more lighting fixtures needed on each boom, the heavier and more cumbersome the units become, in addition to the primary problem of presenting a greater surface area and therefore a greater wind load, which presents problems with wind resistance during windy or stormy days. There is therefore a continuing need for a mobile boom structure which allows the remote tilting of the light racks to reduce the chances of damage in high winds.
It is therefore an object of this invention to provide a mobile lighting fixture, method and boom, which provides a high intensity field of light with less fixtures than previously possible.
It is a further object of this invention to provide a mobile lighting fixture, method and boom which provides universal mobile rigging which can be numerically adjusted to produce lighting qualities and quantities which match computer derived models. It is a further object of this invention to provide a mobile lighting fixture, method and boom which provides a higher intensity beam, utilizing HMI lamps, by using hemispherical dish reflectors and orienting the lamps so that the lamp long axis extends from the center of the reflector outward.
A further object of this invention is to provide a mobile lighting fixture, method and boom which has individual vertical and horizontal adjustment capabilities.
Another object of this invention is to provide a mobile lighting fixture, method and boom which resolves heat, light control, electrical and structural problems.
Another object of this invention is to provide a mobile lighting fixture, method and boom which efficiently captures and consolidates the light in individual lamps and multiple lamps.
Another object of this invention is to provide a mobile lighting fixture, method and boom whereby the lamps can be misaligned and then easily moved back to a predetermined orientation according to the desired numerically adjustable lighting qualities and quantities.
Another object of this invention is to provide a mobile lighting fixture, method and boom whereby the lamps are shock-dampened, but yet will not become misaligned, by even fractions of an inch.
Another object of this invention is to provide a mobile lighting fixture, method and boom whereby the most heat sensitive spots of the lamps are mechanically cooled and maintained at required temperatures to give maximum light beam efficiency without danger of lamp destruction.
A further object of this invention is to provide a mobile lighting fixture, method and boom wherein the fixtures are lightweight, durable, simple, and have a minimum number of parts.
A further object of this invention is to provide a mobile lighting fixture, method and boom which can adjustably tilt by means of remote control.
Another object of this invention is to provide a mobile lighting fixture, method and boom wherein the boom is extensible and collapsible and adjustable, while at the same time allowing tilting of the light rack.
Another object of the invention is to provide a mobile lighting fixture, method and boom which is easily transported, erected, and operated.
Another object of this invention is to provide a mobile light fixture, method and boom which is durable, economical, and versatile.